Thermoplastic container body



Sept. 12, 1967 c.w. SCHILD ETAL 3,341,059

' THERMOPLASTIC CONTAINER BODY Filed Feb. 18. 1966 United States Patent O 3,341,059 THERMOPLASTIC CONTAINER BODY Charles William Schild, Cary, and Roland Norbert Wendricks, Barrington, Ill., assignors to American Can Company, New York, N.Y., a corporation of New Jersey Filed Feb. 18, 1966, Ser. No. 528,452 1 Claim. (Cl. 220-67) This is a continuation in part of our copending application Serial No. 331,619 filed December 18, 1963.

The present invention relates to a tubular container body composed essentially of a thermoplastic material, and in particular to the various aspects of the shape of such a body including a peripheral flange thereon, which flange is particularly constructed to inter-engage with a metal end closure in a doubleseam to form a tight, abuseresistant, packed and closed container.

Because of their many desirable properties, e.g. availability, relatively low cost, easy formability into widely varying shapes, inertness, etc. synthetic thermopl-astic resins are |being used more land more in the packaging industry. However, with containers formed from these thermopl-astics, as with any other packaging material, there is a problem of closing the open end of the container after filling with a desired product in a quick, easy, economical and, above all, tight and abuse-resistant manner.

The standard methods of closing -a container made from thermoplastic, such as heat sealing, while being effective to provide adequate seal, are relatively slow and expensive and usually require a plastic-to-plastic seal. Metal closures have many advant-ages due at least in part to their strength and low cost. However, although at first glance it might be considered obvious to doubleseam a metal end closure onto a thermoplastic body in the same manner as has been done heretofore between metal ends and metal bodies, effecting such a plastic-metal doubleseam has been fraught with many problems.

Thermoplastics lack the combined properties of resiliency, stiffness and hardness found in metals causing the former to flow and Ibecome permanently deformed when subjected to sufiicient stress and, if the stress is severe enough, to fracture or be cut.

It is, therefore, an object of the present invention to provide a container, the body portion of which is composed essentially of thermoplastic having a construction particularly adapting it to readily receive and retain in tight engagement a metal end closure.

Another object is to provide a container of the character described having a body particularly adapted to retain a metal end closure thereon in a doubleseam.

A further object is to provide a -container composed principally of thermoplastic which, when it is filled and has fa metal end closure double-seamed thereon, is liquidtight and highly abuse-resistant.

Yet another object is to provide a container of the character described which is easily handleable during the various stages of its use on its way to the ultimate consumer. t

Yet a further object is to provide a container of the lcharacter described which is stable throughout its useful life.

Still another object is to provide a container `formed of thermoplastic which is well suited for the packaging of various commodities and is economical to make and use.

Numerous other objects and advantages of the invention will be apparent as it is better understood from the following description which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

Patented Sept. 12, 1967 ICC The above objects are accomplished by providing Ia tubular body and integral end wall both composed essentially of thermoplastic and formed in the same operation. The body has a peripheral flange surrounding the open end of the body opposite said end wall, which fiange is particularly constructed and dimensioned to receive and be interfolded with a metal end closure in a doubleseam to secure the metal closure to the body.

Referring to the drawings:

FIG. 1 is a plan view of the Icontainer of the instant invention;

FIG. 2 is an elevational view of the subject container; and

FIG. 3 is an enlarged fragmentary sectional View taken substantially along line 3-3 of FIG. 2.

As a preferred or exemplary embodiment of the instant invention, FIG. 2 shows a container generally designated 10 composed essentially of a thermoplastic synthetic resin. The container 10 may have a variety of transverse crosssectional shapes, e.g. round, rectangular, oval, etc. However, as explained more fully hereinafter, it is preferred that the container 10 have a generally cylindrical configuration, i.e. be substantially circular in transverse crosssection.

The synthetic resin composing the container 10 may be any of those known in the art having utility in the packing field. Examples of-such synthetic resins are polymers of ethylenically unsaturated monomers, such as polyolefins (polyethylene, polypropylene) polystyrene, vinyl resins (polyvinyl chloride, polyvinylidene chloride, copolymers -of ethylene and acrylic acid or vinyl acetate), polyamides such as nylon (polyhexamethyleneadipamide) and polyesters such as Mylar (polyethylene terephthalate).

The container 10 is composed of a substantially tubular body 12 closed at its lower end by means of a bottom 14 integral with and formed at the same time as the body 12. The container 10 can be formed with the body 12 and bottom 14 integral -by means well known in the art such as blow molding or thermoforming. The center panel 16 of the bottom 14 is dished or recessed inwardly an appreciable amount, e.g. approximately 1A". It has been found that when the container 10 is filled with a relatively heavy product such as motor oil, the center panel 16 tends to distend outwardly due to the weight of this product. If the center panel 16 is not sufficiently recessed within the body, the panel extends or bulges beyond the lower periphery of the body 12 giving the bottom 14 a convex or rounded configuration. Such a configuration causes the filled and closed container to be unstable and rock, causing difficulties in storage and handling in automatic equipment.

An outwardly arcuate peripheral bead 18 surrounds the body 12 -at its lower periphery adjacent the bottom 14. A similar peripheral fbead 20 surrounds the body 12 adjacent its upper open end. The high points 22, 24 of each bead 18, 20 respectively are equi-distant in a radial direction from the longitudinal axis of the container 10. This radial` distance is greater than the radial distance from the longitudinal axis to any point on the intermediate portion of the body 12 between the beads 18, 20. In other words, the beads 18, 20 and in particular their high points 22, 24 extend beyond the periphery of the intermedi-ate portion of the body 12. This construction enables the preferred cylindrical configuration of the container 10 to roll readily along runways in the handling thereof after it has been filled and sealed without the intermediate body portion contacting the runways or handling equipment which contact could cause abrasion and marring of any decoration thereon. The beads 18, 20 also protect the intermediate body portion from undesirable contact by adjacent containers during handling, packing or storage.

A peripheral flange 26 integral with the tbody 12 surrounds the upper open end 28 of the container 10. Unexpectedly it has been found that the thickness, i.e. the distance between its upper and lower flat face, of the flange 26 is critical to enable the flange to be quickly and easily interfolded with the peripheral flange of a sheet metal end (not shown) to form a liquid-tight, abuseresistant doubleseam. In the container of the instant invention, the flange thickness must be less than the thickness of substantially all of the body side wall; is equal to or greater than the thickness of the bottom; and is in the range of from 0.018l to 0.022", and preferably averages about 0.020".

Certainly the radial length of the flange 26 has a bearing upon the quality of the doubleseam and the efficiency in forming the seam; but this length dimension does not have the criticality of thickness dimension. Further, aside from the requirement that the flange 26 must have a minimum length sufllcient to be grasped by the periphery of the metal end, the so-called cover hook, unlike the thickness limitation, its optimum and maximum length will vary with the dimensions of the container and thus the cover hook. However, for the container of the instant invention the flange radial length measured from the outside of the body wall should fall within the range of 0.065 to 0.095" and preferably about 0.090.

In order to be self-supporting and to withstand abuse during its useful life, the side wall of the body 12 has a thickness, except for a small portion adjacent the integral bottom, in the range of 0.026 to 0.036 and preferably averaging about 0.031. As mentioned above and as illustrated in FIG. 3, the flange 26 is appreciably thinner than the wall thickness of the body 12. However, contrary to prior art doubleseaming practice wherein the body flange is made as thick or thicker than the lbody side wall, the thin flange of the instant container produces a stronger, more abuse-resistant doubleseam.

As shown in the drawing, the flange 26 extends beyond the high points 22, 24 of the beads 18, 20. However, after formation of the doubleseam, the flange 26, in association with the periphery of the metal end, is folded back twards the adjacent outside surface of the body wall portion 30 between the bead 20 and open end 28. The body wall portion 30 is substantially cylindrical and provides space for accommodating the doubleseam, which, after formation, will not extend beyond the high points of the beads 18, 20. Also, as shown in the drawings, the flange 26 extends substantially perpendicularly out from the body Wall portion 30, i.e. the included angle between the fla-nge and body portion 30 is approximately 90. The orientation of the flange 26 can range from slightly below to somewhat above the horizontal so that the included angle ranges about from 85 to 135.

It has been found that with the construction of the instant invention, equivalent liqui-d-tightness and abuseresistance can be obtained both with and without the presence of a rubbery end lining compound or gasketing material conventionally used in metal-to-metal doubleseams. The elimination of this gasket permits an appreciable saving in material, equipment and time in the manu-facture of the containers embodying the instant invention.

Comparative tests were conducted wherein sheet metal end closures were double-seamed in the same apparatus onto thermoplastic containers having a flange with an average thickness of 0.021 and a flange length of about 0.090" according to the instant invention and those having a similar construction but wherein their peripheral flange had an average thickness of 0.031" and a length of about 0.090". With the containers of the subject invention the doubleseam was slim, tight and had the cover hook well wrapped around the flange; whereas with the other containers having the thicker flange the doubleseam was bulky with the cover hook not extending to the underside of the flange. Both types of containers were subjected to controlled abuse testing using a pendulum impact tester which strikes the side of the container in the doubleseam area with a controllable impact. Such testing simulates commercial handling abuse; and provides a reliable cornparison of variables within containers of the same general type. Under this control testing the thick flange containers failed a significantly greater number of times, mostly by seam pull out but occasionally by side wall fracture, than the containers of the instant invention.

It is thought that the invention and many of its attendant advantages will 'be understood from the foregoing descriptionv and it will be apparent that various changes may be made in the form, construction and arrangement of the parts without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

We claim:

A container having a body and one end closure integral therewith, both formed from thermoplastic material, the end of said body opposite said closure being open;

said body having a substantially uniform wall thickness throughout its area rendering the body self-supporting and able to withstand abuse during its normal life;

a peripheral flange integral with said body and surrounding said open end;

said flange extending substantially perpendicularly outwardly from the body wall adjacent said flange and being adapted to be interfolded with the periphery of a metal end in a doubleseam to close said open end;

said flange being of a thickness substantially two-thirds that of the side wall of said body thereby facilitating interfolding of the flange with the periphery of said metal end whereby said doubleseam is liquid-tight and abuse-resistant.

References Cited UNITED STATES PATENTS 24,772 7/ 1859 Wilson et al. 220-67 1,605,229 11/ 1926 Hartmann 220-67 1,824,907 9/ 1931 Lermer 229-516 2,285,220 6/1942 Morrell 220-67 3,027,044 3/ 1962 Winstead 220-72 XR 3,139,131 6/1964 Hutchinson 220-67 XR 3,170,592 2/1965 Ullman et al 220-72 XR FOREIGN PATENTS 873,169 7/1961 Great Britain. 575,292 4/1924 France.

THERON E. CONDON, Primary Examiner.

I R. GARRETT, Assistant Examiner, 

